This invention relates to an improvement in a mechanical seal which prevent the leakage of fluid through relatively rotatable sliding contact surfaces. There are many sliding contact portions in industrial machinery such as the compressors of car coolers and other pumping and compressing apparatus for fluids. As is well known when considering the operation of a mechanical seal in a car cooler or radiator system, the sealed pressurized fluid is either a liquid or a mixture of a gas and a liquid. In such a prior art system, the sealed pressurized fluid is sealed in on the outside of the seal and an external fluid is disposed on the inside of the seal. It is specifically desired to avoid the leakage flow of the pressurized fluid toward the external fluid such as gas. The performance of such sliding contact portions has great influence on the durability and reliability of the machines.
In the ordinary prior art mechanical seal, a follower ring which rotates together with the rotary shaft is brought into sliding contact with a seating ring on the stationary side which is also carried by the rotary shaft. The leakage of a fluid from the outside to the inside of the sliding contact surfaces is avoided by a mechanical means. In order to improve the sealing effect between the contact surfaces, several countermeasures have been taken. For example, the pressure per unit area between the contact surfaces is increased by intensifying the pressure between the seating ring and the follower ring or durable sealing surfaces are formed by selecting the material of contact surfaces. However, it is impossible to avoid the occurrence of coarseness of the contact surfaces and the wear or other changes of the contact surfaces during prolonged use. Especially in the case of the mechanical seal for the compressor of a car cooler or the like, where severe conditions of varying temperature and exerted vibration enhances the probability of the leakage of fluid. Therefore, radical measures against such defects have long been desired.